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One of the world's leading neuroscientists, Christof Koch, has some fascinating theories about consciousness and computers. He believes it is possible, in principle, for a computer to become truly conscious, but only in a very specific way. Transhumanists the world over will applaud. But not so fast. If Koch's views are correct, it also means that the ultimate hope of many transhumanists -- that is, to eventually upload their mind and live forever inside a computer -- is never going to happen.

[C]onsciousness is a property of complex systems that have a particular “cause-effect” repertoire. They have a particular way of interacting with the world, such as the brain does, or in principle, such as a computer could. If you were to build a computer that has the same circuitry as the brain, this computer would also have consciousness associated with it. It would feel like something to be this computer. However, the same is not true for digital simulations... The analogy, and it’s a very good one, is that you can make pretty good weather predictions these days [with digital simulations]. You can predict the inside of a storm. But it’s never wet inside the computer. You can simulate a black hole in a computer, but space-time will not be bent. Simulating something is not the real thing.

It’s the same thing with consciousness. In 100 years, you might be able to simulate consciousness on a computer. But it won’t experience anything. Nada. It will be black inside. It will have no experience whatsoever, even though it may have our intelligence and our ability to speak.

So, according to the theory that Koch describes, a computer that is closely structured like a brain could become conscious, but software never will. Here's why that puts a damper on transhumanists' ultimate hope of digital immortality:

As the recent movie Transcendence depicted, the process of supposedly "uploading" a mind simply means digitally copying and simulating (via software) all the connections and information associated with a person's brain. It would be like having a 3-D, interactive simulation of your house saved on your computer, down to every board and nail. But, as Koch said, a simulation is not the real thing. If consciousness is only possible when you get physical parts configured in a certain way, then merely configuring digital "parts" in the same way will not have the same effect. You cannot actually live in the digital simulation of your house.

Even if Koch is wrong, though, there are further reasons why the future envisioned by transhumanists is likely pure fantasy. Pretend for just a moment that digital simulations could really be conscious. A person could still not achieve immortality by making a digital copy of their brain for a very simple reason: A copy is not one and the same object as the original; they're two different objects.

According to Leibniz' law, known as the "indiscernibility of identicals," if two objects are one and the same object, then they will have all the same properties. But a human brain and a digital brain do not have all the same properties for obvious reasons (one is made of physical, organic matter; while one is a virtual simulation). Hence, the consciousness of your brain (what we call "you") is one object, while the (assumed) consciousness of a digital simulation is another. They're two distinct consciousnesses. They can no more be the same person than identical twins could be. Therefore, making a digital copy of your consciousness does nothing to ensure that you will live forever, it just means the copy you made of yourself will "live" after you die. That's not immortality.

Moreover, there are good reasons to think that consciousness is more mysterious than Koch believes. It's possible that consciousness cannot be explained by physical components. Perhaps, instead, conscious experience is better understood as the property of something like a soul -- something that cannot simply be copied or "uploaded."

Koch's theory is attractive for many reasons. He takes the qualia of conscious experience seriously, even though he thinks it is ultimately caused by physical components. Also, he correctly sees how the functionalist view of consciousness has ethical problems, and he speculates how his theory could help. But I find his theory most intriguing for the reasons I've explained above: because, even though the possibility of computer consciousness fulfills a major hope of the transhumanist movement, Koch's theory also means that the primary goal of being uploaded into the cloud is ultimately unrealistic. Transhumanists still have other hopes of immortality through human longevity research. But the pinnacle event of their religion -- the rapture-like "singularity" -- probably won't be what they've hoped for, if it happens at all.